Liquid crystal display device

ABSTRACT

A display device includes a first substrate formed with a first gate line, a first source line, a first thin film transistor, and a first light shielding unit; a second substrate disposed opposite to the first substrate; and a first liquid crystal layer disposed between the first substrate and the second substrate. The first light shielding unit is disposed between the first thin film transistor and the first liquid crystal layer, and overlaps at least a part of a first channel region of the first thin film transistor in planar view.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP2017-044783 filed on Mar. 9, 2017, the contents of which are herebyincorporated by reference into this application.

TECHNICAL FIELD

The present invention relates to a liquid crystal display device, and,more particularly to a liquid crystal display device with improvedcontrast.

BACKGROUND

In a liquid crystal display device, when light from a backlight, lightfrom an outside (natural light), or light in which the light from thebacklight and the natural light is scattered by a liquid crystal layer(scattered light) is incident on a channel region of a thin filmtransistor, a characteristic of the thin film transistor generallychanges, which results in degradation of display quality. For example, amethod for enlarging a region of a black matrix or a method forproviding a light shielding layer on a backlight side of the thin filmtransistor is conceivable as a method for solving the problem. However,in these methods, an opening ratio of a pixel is degraded, or aconfiguration becomes complicated.

A technique, in which two display panels overlap each other and an imageis displayed on each display panel based on an input video signal, isconventionally proposed to improve contrast of a liquid crystal displaydevice (for example, see International Publication WO2007/040127).Specifically, for example, a color image is displayed on a front-side(observer-side) display panel in two display panels disposed back andforth, and a black-and-white image is displayed on a rear-side(backlight-side) display panel, thereby improving contrast. In a liquidcrystal display device including two display panels, the display paneldisposed on the backlight side is easily influenced by the back light orthe scattered light, and the characteristic of the thin film transistoris easy to change.

Thus, in the conventional liquid crystal display device, the displayquality is degraded due to the light incident on the channel region ofthe thin film transistor.

The present disclosure is made in view of the above situation, and anobject of the present disclosure is to provide a liquid crystal displaydevice that can prevent the degradation of the display quality due tothe light incident on the channel region of the thin film transistor.

SUMMARY

In one general aspect, a display device of the instant applicationincludes a first substrate formed with a first gate line, a first sourceline, a first thin film transistor, and a first light shielding unit; asecond substrate disposed opposite to the first substrate; and a firstliquid crystal layer disposed between the first substrate and the secondsubstrate. The first light shielding unit is disposed between the firstthin film transistor and the first liquid crystal layer, and overlaps atleast a part of a first channel region of the first thin film transistorin planar view.

The above general aspect may include one or more of the followingfeatures.

A common electrode may be further formed on the first substrate. Thefirst light shielding unit may be made of a metallic material, andelectrically connected to the common electrode.

A common wiring through which a common voltage is supplied to the commonelectrode may be further formed on the first substrate. The first lightshielding unit may be integral with the common wiring.

An organic insulator film may be further formed on the first substrate,and the organic insulator film may be disposed between the first thinfilm transistor and the first light shielding unit.

The liquid crystal display device may further include a backlight. Thefirst liquid crystal layer may be disposed between the backlight and thefirst substrate.

The second substrate may include a black matrix. The black matrix mayoverlap at least a part of the first channel region in planar view, andthe first light shielding unit may include an overlapping region wherethe first light shielding unit overlaps the black matrix and anon-overlapping region where the first light shielding unit does notoverlap the black matrix.

The liquid crystal display device may further include a third substrateformed with a second gate line, a second source line, and a second thinfilm transistor; a fourth substrate disposed opposite to the thirdsubstrate; and a second liquid crystal layer disposed between the thirdsubstrate and the fourth substrate. The second substrate may be disposedbetween the first liquid crystal layer and the second liquid crystallayer.

The liquid crystal display device may further include a backlight. Thefirst liquid crystal layer may be disposed between the backlight and thesecond substrate.

The liquid crystal display device may further include: a third substrateformed with a second gate line, a second source line, and a second thinfilm transistor; a fourth substrate disposed opposite to the thirdsubstrate; and a second liquid crystal layer disposed between the thirdsubstrate and the fourth substrate. The first substrate may be disposedbetween the first liquid crystal layer and the second liquid crystallayer.

The liquid crystal display device may further include a backlight. Thefirst liquid crystal layer may be disposed between the backlight and thefirst substrate.

A second light shielding unit may be further formed on the thirdsubstrate, and the second light shielding unit may be disposed betweenthe second thin film transistor and the second liquid crystal layer, andmay overlap at least a part of a second channel region of the secondthin film transistor in planar view.

In the liquid crystal display device of the present disclosure, thedegradation of the display quality due to the light incident on thechannel region of the thin film transistor can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a schematic configuration ofliquid crystal display device of a first exemplary embodiment;

FIG. 2 is a view illustrating a schematic configuration of liquidcrystal display device of the first exemplary embodiment;

FIG. 3 is a plan view illustrating a schematic configuration of displaypanel LCP1 of the first exemplary embodiment;

FIG. 4 is a plan view illustrating a schematic configuration of displaypanel LCP2 of the first exemplary embodiment;

FIG. 5 is a sectional view taken along line A-A in FIGS. 3 and 4;

FIGS. 6A and 6B are plan views each illustrating a dispositionrelationship between pixel of display panel LCP1 and pixel of displaypanel LCP2;

FIG. 7 is a plan view illustrating a configuration of pixel of displaypanel LCP1;

FIG. 8 is a plan view illustrating a configuration of pixel of displaypanel LCP1;

FIG. 9 is a plan view illustrating a configuration of pixel of displaypanel LCP2;

FIG. 10 is a plan view illustrating a configuration of pixel of displaypanel LCP2;

FIG. 11 is a sectional view taken along line B-B′ in FIGS. 7 to 10;

FIG. 12 is a sectional view taken along line C-C′ in FIGS. 7 to 10;

FIG. 13 is a plan view illustrating another configuration of pixel ofdisplay panel LCP2 of the first exemplary embodiment;

FIGS. 14A and 14B are plan views each illustrating a dispositionrelationship between pixel of display panel LCP1 and pixel of displaypanel LCP2 of the first exemplary embodiment;

FIG. 15 is a sectional view illustrating a configuration of pixel ofdisplay panel LCP of the second exemplary embodiment;

FIG. 16 is a sectional view illustrating another configuration of pixelof display panel LCP of the second exemplary embodiment; and

FIG. 17 is a plan view illustrating another pixel configuration ofdisplay panel of the first exemplary embodiment.

DETAILED DESCRIPTION

Hereinafter, an exemplary embodiment of the present disclosure will bedescribed with reference to the drawings. A liquid crystal displaydevice according to one exemplary embodiment includes a plurality ofdisplay panels that display images, a plurality of driving circuits (aplurality of source drivers and a plurality of gate drivers) that drivethe display panels, a plurality of timing controllers that control thedriving circuits, an image processor that performs image processing onan input video signal input from an outside and outputs image data toeach of the timing controllers, and a backlight that irradiates theplurality of display panels with light from a rear surface side. Anumber of the plurality of display panels is not limited to two, and maybe more When viewed from the observer side, the plurality of displaypanels are disposed while overlapping each other in a front-backdirection. An image is displayed on each of the display panels. A liquidcrystal display device LCD of a first exemplary embodiment including twodisplay panels will be described below by way of example, and a liquidcrystal display device LCD of a second exemplary embodiment including aone display panels will be described below by way of example.

First Exemplary Embodiment

FIG. 1 is a perspective view illustrating a schematic configuration ofliquid crystal display device LCD of the exemplary embodiment. Asillustrated in FIG. 1, liquid crystal display device LCD includesdisplay panel LCP1 disposed at a position (front side) closer to anobserver, display panel LCP2 disposed at a position (rear side) fartheraway from the observer with respect to display panel LCP1, adhesivelayer ADL in which display panel LCP1 and display panel LCP2 adhere toeach other, backlight BL disposed on the rear surface side of displaypanel LCP2, and front chassis FS that covers display panel LCP1 anddisplay panel LCP2 from the display surface side.

FIG. 2 is a view illustrating the schematic configuration of liquidcrystal display device LCD of the exemplary embodiment. As illustratedin FIG. 2, display panel LCP1 includes first source driver SD1 and firstgate driver GD1, and display panel LCP2 includes second source driverSD2 and second gate driver GD2. Liquid crystal display device LCD alsoincludes first timing controller TCON1 that controls first source driverSD1 and first gate driver GD1, second timing controller TCON2 thatcontrols second source driver SD2 and second gate driver GD2, and imageprocessor IPU that outputs image data to first timing controller TCON1and second timing controller TCON2. For example, display panel LCP1displays a color image in first image display region DISP1 according tothe input video signal, and display panel LCP2 displays ablack-and-white image in second image display region DISP2 according tothe input video signal. Image processor IPU receives input video signalData transmitted from an external system (not illustrated), performsknown image processing on input video signal Data, and then outputsfirst image data DAT1 to first timing controller TCON1 and outputssecond image data DAT2 to second timing controller TCON2. Imageprocessor IPU also outputs a control signal (not illustrated in FIG. 2)such as a synchronizing signal to first timing controller TCON1 andsecond timing controller TCON2. For example, first image data DAT1 isimage data for displaying the color image, and second image data DAT2 isimage data for displaying the monochrome image.

FIG. 3 is a plan view illustrating a schematic configuration of displaypanel LCP1 of the first exemplary embodiment, and FIG. 4 is a plan viewillustrating a schematic configuration of display panel LCP2 of thefirst exemplary embodiment. FIG. 5 is a sectional view taken along lineA-A in FIGS. 3 and 4.

The schematic configuration of display panel LCP1 will be described withreference to FIGS. 3 and 5. As illustrated in FIG. 5, display panel LCP1includes thin film transistor substrate TFTB1 disposed on the side ofbacklight BL, counter substrate CF1, which is disposed on the observerside while being opposite to thin film transistor substrate TFTB1, andliquid crystal layer LC1 disposed between thin film transistor substrateTFTB1 and counter substrate CF1. Polarizing plate POL2 is disposed onthe side of backlight BL of display panel LCP1, and polarizing platePOL1 is disposed on the observer side.

In thin film transistor substrate TFTB1, as illustrated in FIG. 3, aplurality of source lines SL1 extending in a first direction (forexample, a column direction), and a plurality of gate lines GL1extending in a second direction (for example, a row direction) differentfrom the first direction are formed, and thin film transistor TFT1 isformed close to an intersection between each of the plurality of sourcelines SL1 and each of the plurality of gate lines GL1. In plan view ofdisplay panel LCP1, a region surrounded by two source lines SL1 adjacentto each other and two gate lines GL1 adjacent to each other is definedas one pixel PIX1, and a plurality of pixels PIX1 are disposed in amatrix form (the row direction and the column direction). The pluralityof source lines SL1 are disposed at equal intervals in the rowdirection, and the plurality of gate lines GL1 are disposed at equalintervals in the column direction. In thin film transistor substrateTFTB1, pixel electrode PIT1 is formed in each pixel PIX1, and one commonelectrode CIT1 (see FIG. 14) common to the plurality of pixels PIX1 isformed. Drain electrode DE1 (see FIG. 14) constituting thin filmtransistor TFT1 is electrically connected to source line SL1, sourceelectrode SE1 (see FIG. 14) is electrically connected to pixel electrodePIT1 through contact hole CH1 (see FIG. 14), and gate electrode GE1 (seeFIG. 14) is electrically connected to gate line GL1.

As illustrated in FIG. 5, a light transmission unit that transmits lightand black matrix BM1 (a light shielding unit) that obstructs the lighttransmission are formed in counter substrate CF1. A plurality of colorfilters FIL (colored layer) are formed in the light transmission unitaccording to each pixel PIX1. The light transmission unit is surroundedby black matrix BM. For example, the light transmission unit is formedinto a rectangular shape. The plurality of color filters FIL include redcolor filters FILR (red layer) made of a red (R color) material totransmit red light, green color filters FILG (green layer) made of agreen (G color) material to transmit green light, and blue color filtersFILB (blue layer) made of a blue (B color) material to transmit bluelight. Red color filters FILR, green color filters FILG, and blue colorfilters FILB are repeatedly arrayed in the row direction in this order,identical-color filters FIL are arrayed in the column direction, andblack matrix BM1 is formed at a boundary between color filters FILadjacent to each other in the row direction and the column direction.According to each color filter FIL, as illustrated in FIG. 3, theplurality of pixels PIX1 include red pixels PIXR corresponding to redcolor filter FILR, green pixels PIXG corresponding to green color filterFILG, and blue pixels PIXB corresponding to blue color filter FILB. Indisplay panel LCP1, red pixels PIXR, green pixels PIXG, and blue pixelsPIXB are repeatedly arrayed in the row direction in this order, andpixels PIX1 having the identical color are arrayed in the columndirection.

First timing controller TCON1 has a known configuration. For example,based on first image data DAT1 and first control signal CS1 (such as aclock signal, a vertical synchronizing signal, and a horizontalsynchronizing signal), which are output from image processor IPU, firsttiming controller TCON1 generates various timing signals (data startpulse DSP1, data clock DCK1, gate start pulse GSP1, and gate clock GCK1)to control first image data DA1 and drive of first source driver SD1 andfirst gate driver GD1 (see FIG. 3). First timing controller TCON1outputs first image data DA1, data start pulse DSP1, and data clock DCK1to first source driver SD1, and outputs gate start pulse GSP1 and gateclock GCK1 to first gate driver GD1.

First source driver SD1 outputs a data signal (data voltage)corresponding to first image data DA1 to source line SL1 based on datastart pulse DSP1 and data clock DCK1. First gate driver GD1 outputs agate signal (gate voltage) to gate lines GL1 based on gate start pulseGSP1 and gate clock GCK1.

First source driver SD1 supplies the data voltage to each source lineSL1, and first gate driver GD1 supplies the gate voltage to each gateline GL1. Common voltage Vcom is supplied from a common driver (notillustrated) to common electrode CIT1 through a common wiring CMT1 (seeFIG. 6). When the gate voltage (gate-on voltage) is supplied to gateline GL1, thin film transistor TFT1 connected to gate line GL1 is turnedon, and the data voltage is supplied to pixel electrode PIT1 throughsource line SL1 connected to thin film transistor TFT1. An electricfield is generated by a difference between the data voltage supplied topixel electrode PIT1 and common voltage Vcom supplied to commonelectrode CIT1. The liquid crystal is driven by the electric field, andtransmittance of the light emitted from backlight BL is controlled,thereby displaying an image. In display panel LCP1, a color image isdisplayed by the supply of a desired data voltage to source line SL1connected to pixel electrode PIT1 of each of pixel PIX1.

The configuration of display panel LCP2 will be described below withreference to FIGS. 4 and 5. As illustrated in FIG. 5, display panel LCP2includes thin film transistor substrate TFTB2 disposed on the side ofbacklight BL, counter substrate CF2, which is disposed on the observerside while being opposite to thin film transistor substrate TFTB2, andliquid crystal layer LC2 disposed between thin film transistor substrateTFTB2 and counter substrate CF2. Polarizing plate POL4 is disposed onthe side of backlight BL of display panel LCP2, and polarizing platePOL3 is disposed on the observer side. Adhesive layer ADL is disposedbetween polarizing plate POL2 of display panel LCP1 and polarizing platePOL3 of display panel LCP2.

In thin film transistor substrate TFTB2, as illustrated in FIG. 4, aplurality of source lines SL2 extending in the column direction, and aplurality of gate lines GL2 extending in the row direction are formed,and thin film transistor TFT2 is formed close to the intersectionbetween each of the plurality of source lines SL2 and each of theplurality of gate lines GL2. In plan view of display panel LCP2, aregion surrounded by two source lines SL2 adjacent to each other and twogate lines GL2 adjacent to each other is defined as one pixel PIX2, anda plurality of pixels PIX2 are disposed in a matrix form (the rowdirection and the column direction). The plurality of source lines SL2are disposed at equal intervals in the row direction, and the pluralityof gate lines GL2 are disposed at equal intervals in the columndirection. In thin film transistor substrate TFTB2, pixel electrode PIT2is formed in each pixel PIX2, and one common electrode CIT2 (see FIG.14) common to the plurality of pixels PIX2 is formed. Drain electrodeDE2 constituting thin film transistor TFT2 is electrically connected tosource line SL2, source electrode SE2 (see FIG. 14) is electricallyconnected to pixel electrode PIT2 through contact hole CH2 (see FIG.14), and gate electrode GE2 (see FIG. 14) is electrically connected togate line GL2.

In counter substrate CF2 (See FIG. 5), the light transmission unit thattransmits light is formed. The color filter (colored portion) is notformed in the light transmission unit, but overcoat film OC2 is formedin the light transmission unit.

Second timing controller TCON2 has a known configuration. For example,based on second image data DAT2 and second control signal CS2 (such as aclock signal, a vertical synchronizing signal, and a horizontalsynchronizing signal), which are output from image processor IPU, secondtiming controller TCON2 generates various timing signals (data startpulse DSP2, data clock DCK2, gate start pulse GSP2, and gate clock GCK2)to control second image data DA2 and drive of second source driver SD2and second gate driver GD2 (see FIG. 4). Second timing controller TCON2outputs second image data DA2, data start pulse DSP2, and data clockDCK2 to second source driver SD2, and outputs gate start pulse GSP2 andgate clock GCK2 to second gate driver GD2.

Second source driver SD2 outputs the data voltage corresponding tosecond image data DA2 to source line SL2 based on data start pulse DSP2and data clock DCK2. Second gate driver GD2 outputs the gate voltage togate lines GL2 based on gate start pulse GSP2 and gate clock GCK2.

Second source driver SD2 supplies the data voltage to each source lineSL2, and second gate driver GD2 supplies the gate voltage to each gateline GL2. The common driver supplies common voltage Vcom to commonelectrode CIT2 through a common wiring CMT1 (see FIG. 6). When the gatevoltage (gate-on voltage) is supplied to gate line GL2, thin filmtransistor TFT2 connected to gate line GL2 is turned on, and the datavoltage is supplied to pixel electrode PIT2 through source line SL2connected to thin film transistor TFT2. An electric field is generatedby a difference between the data voltage supplied to pixel electrodePIT2 and common voltage Vcom supplied to common electrode CIT2. Theliquid crystal is driven by the electric field, and transmittance of thelight emitted from backlight BL is controlled, thereby displaying animage. In display panel LCP2, a color image is displayed by the supplyof a desired data voltage to source line SL1 connected to pixelelectrode PIT1 of each of red pixel PIXR, green pixel PIXG, and bluepixel PIXB.

FIGS. 6A and 6B are plan views each illustrating a dispositionrelationship between pixel PIX1 of display panel LCP1 and pixel PIX2 ofdisplay panel LCP2. Liquid crystal display device LCD is configured suchthat a number of pixels PIX1 (a number of pixel electrodes PIX1) perunit area of display panel LCP1 is equal to a number of pixels PIX2 (anumber of pixel electrodes PIX2) per unit area of display panel LCP2. Anarea of one pixel PIX1 is equal to an area of one pixel PIX2.

Each of FIGS. 7 and 8 is a plan view illustrating a configuration ofpixel PIX1 of display panel LCP1. FIG. 7 illustrates a state in whichcounter substrate CF1 is seen through, and FIG. 8 illustrates thin filmtransistor substrate TFTB1 while black matrix BM1 of counter substrateCF1 overlaps thin film transistor substrate TFTB1.

As illustrated in FIG. 7, in thin film transistor TFT1, drain electrodeDE1 is electrically connected to source line SL1, a part of drainelectrode DE1 overlaps semiconductor layer SI1, source electrode SE1 iselectrically connected to pixel electrode PIT1 through contact hole CH1,and a part of source electrode SE1 overlaps semiconductor layer SI1.Gate electrode GE1 is electrically connected to gate line GL1, and apart of gate electrode GE1 overlaps semiconductor layer SI1. Commonwiring CMT1 (a half tone portion in FIG. 7) includes a portion (firstportion CMT1 a) extending in the column direction and a portion (secondportion CMT1 b) extending in the row direction, first portion CMT1 aoverlaps source line SL1 in planar view, and second portion CMT1 boverlaps at least a part of the channel region of thin film transistorTFT1 in planar view. Second portion CMT1 b may overlap the whole channelregion of thin film transistor TFT1 or the whole region where thin filmtransistor TFT1 is formed in planar view. Common wiring CMT1 is made ofa metallic material (such as copper (Cu), molybdenum (Mo), and aluminum(Al)), and electrically connected to common electrode CIT1. Firstportion CMT1 a and second portion CMT1 b may integrally be formed, orseparately be formed while electrically connected to each other.

As illustrated in FIG. 8, in black matrix BM1 (a half tone portion inFIG. 8), a portion extending in the column direction overlaps sourceline SL1 in planar view, and a portion extending in the row directionoverlaps gate line GL1 in planar view. A part of black matrix BM1overlaps a part of the channel region of thin film transistor TFT1 inplanar view. Lengths L1(CMT1), L2(CMT1) (see FIG. 7) of common wiringCMT1 (second portion CMT1 b) overlapping the channel region of thin filmtransistor TFT1 are larger than lengths L1(BM1), L2(BM1) (see FIG. 8) ofblack matrix BM1 overlapping the channel region of thin film transistorTFT1, respectively. That is, second portion CMT1 b includes anoverlapping region where second portion CMT1 b overlaps black matrix BM1and a non-overlapping region where second portion CMT1 b does notoverlap black matrix BM1.

Each of FIGS. 9 and 10 is a plan view illustrating a configuration ofpixel PIX2 of display panel LCP2. FIG. 9 illustrates a state in whichcounter substrate CF2 is seen through, and FIG. 10 illustrates thin filmtransistor substrate TFTB2 while black matrix BM2 of counter substrateCF2 overlaps thin film transistor substrate TFTB2.

As illustrated in FIG. 9, in thin film transistor TFT2, drain electrodeDE2 is electrically connected to source line SL2, a part of drainelectrode DE2 overlaps semiconductor layer SI2, source electrode SE2 iselectrically connected to pixel electrode PIT2 through contact hole CH2,and a part of source electrode SE2 overlaps semiconductor layer SI2.Gate electrode GE2 is electrically connected to gate line GL2, and apart of gate electrode GE2 overlaps semiconductor layer SI2. Commonwiring CMT2 (a half tone portion in FIG. 9) includes a portion (firstportion CMT2 a) extending in the column direction and a portion (secondportion CMT2 b) extending in the row direction, first portion CMT2 aoverlaps source line SL2 in planar view, and second portion CMT2 boverlaps at least a part of the channel region of thin film transistorTFT2 in planar view. Second portion CMT2 b may overlap the whole channelregion of thin film transistor TFT2 or the whole region where thin filmtransistor TFT2 is formed in planar view. Common wiring CMT2 is made ofa metallic material (such as copper (Cu), molybdenum (Mo), and aluminum(Al)), and electrically connected to common electrode CIT2. Firstportion CMT2 a and second portion CMT2 b may integrally be formed, orseparately be formed while electrically connected to each other.

As illustrated in FIG. 10, in black matrix BM2 (a half tone portion inFIG. 10), a portion extending in the column direction overlaps sourceline SL2 in planar view, and a portion extending in the row directionoverlaps gate line GL2 in planar view. A part of black matrix BM2overlaps a part of the channel region of thin film transistor TFT2 inplanar view. Lengths L1(CMT2), L2(CMT2) (see FIG. 9) of common wiringCMT2 (second portion CMT2 b) overlapping the channel region of thin filmtransistor TFT2 are larger than lengths L1(BM2), L2(BM2) (see FIG. 10)of black matrix BM2 overlapping the channel region of thin filmtransistor TFT2, respectively. That is, second portion CMT2 b includesan overlapping region where second portion CMT2 b overlaps black matrixBM2 and a non-overlapping region where second portion CMT2 b does notoverlap black matrix BM2.

FIG. 11 is a sectional view taken along line B-B′ in FIGS. 7 to 10, andFIG. 12 is a sectional view taken along line C-C′ in FIGS. 7 to 10.Sectional structures of pixels PIX1, PIX2 will be described below withreference to FIGS. 11 and 12. In display panel LCP1, thin filmtransistor substrate TFTB1 is disposed on the side of backlight BL, andcounter substrate CF1 is disposed on the observer side. In display panelLCP2, thin film transistor substrate TFTB2 is disposed on the observerside, and counter substrate CF2 is disposed on the side of backlight BL.That is, thin film transistor substrate TFTB1 and thin film transistorsubstrate TFTB2 are disposed opposite to each other.

In thin film transistor substrate TFTB1 constituting pixel PIX1 ofdisplay panel LCP1, gate line GL1 and gate electrode GE1 are formed ontransparent substrate SUB2 (glass substrate), and gate insulator filmGSN1 is formed so as to cover gate line GL1 and gate electrode GE1.Source line SL1, drain electrode DE1, source electrode SE1, andsemiconductor layer SI1 are formed on gate insulator film GSN1, andprotective insulator film PAS1 (inorganic insulator film) and organicinsulator film OPAS1 are sequentially formed so as to cover source lineSL1, drain electrode DE1, source electrode SE1, and semiconductor layerSI1. Common electrode CIT1 is formed on organic insulator film OPAS1,and common wiring CMT1 is formed on common electrode CIT1. First portionCMT1 a (see FIG. 11) of common wiring CMT1 overlaps source line SL1 inplanar view, and second portion CMT1 b (see FIG. 12) of common wiringCMT1 overlaps the region where thin film transistor TFT1 is formed inplanar view. Upper insulator film UPAS1 is form so as to cover commonelectrode CIT1 and common wiring CMT1, pixel electrode PIT1 is formed onupper insulator film UPAS1, and alignment film AL2 is formed so as tocover pixel electrode PIT1. Protective insulator film PAS1, organicinsulator film OPAS1, common electrode CIT1, common wiring CMT1 (secondportion CMT1 b), and upper insulator film UPAS1 are partially bored tomake contact hole CH1. A part of pixel electrode PIT1 is electricallyconnected to source electrode SE1 through contact hole CH1.

In counter substrate CF1, black matrix BM1 and color filter FIL (redcolor filter FILR, green color filter FILG, and blue color filter FILB)are formed on transparent substrate SUB1 (glass substrate). Overcoatfilm OC1 is coated on a surface of color filter FIL, and alignment filmAL1 is formed on overcoat film OC1.

In thin film transistor substrate TFTB2 constituting pixel PIX2 ofdisplay panel LCP2, gate line GL2 and gate electrode GE2 are formed ontransparent substrate SUB3 (glass substrate), and gate insulator filmGSN2 is formed so as to cover gate line GL2 and gate electrode GE2.Source line SL2, drain electrode DE2, source electrode SE2, andsemiconductor layer SI2 are formed on gate insulator film GSN2, andprotective insulator film PAS2 and organic insulator film OPAS2 aresequentially formed so as to cover source line SL2, drain electrode DE2,source electrode SE2, and semiconductor layer SI2. Common electrode CIT2is formed on organic insulator film OPAS2, and common wiring CMT2 isformed on common electrode CIT2. First portion CMT2 a (see FIG. 11) ofcommon wiring CMT2 overlaps source line SL2 in planar view, and secondportion CMT2 b (see FIG. 12) of common wiring CMT2 overlaps the regionwhere thin film transistor TFT2 is formed in planar view. Upperinsulator film UPAS2 is form so as to cover common electrode CIT2 andcommon wiring CMT2, pixel electrode PIT2 is formed on upper insulatorfilm UPAS2, and alignment film AL3 is formed so as to cover pixelelectrode PIT2. Protective insulator film PAS2, organic insulator filmOPAS2, common electrode CIT2, common wiring CMT2 (second portion CMT2b), and upper insulator film UPAS2 are partially bored to make contacthole CH2. A part of pixel electrode PIT2 is electrically connected tosource electrode SE2 through contact hole CH2.

In counter substrate CF2, lattice-shape black matrix BM2 is formed ontransparent substrate SUB4 (glass substrate), an opening (lighttransmission unit) of black matrix BM2 and black matrix BM2 are coatedwith overcoat film OC2, and alignment film AL4 is formed on overcoatfilm OC2.

In liquid crystal display device LCD of the first exemplary embodiment,second portion CMT2 b of display panel LCP2 is disposed so as to overlapthe channel region of thin film transistor TFT2 in planar view, so thatan amount of light incident on the channel region can be decreased. Inthe region overlapping the channel region, an area of second portionCMT2 b is larger than an area of black matrix BM2, and second portionCMT2 b is disposed close to the channel region, so that second portionCMT2 b can shield the light that is not completely shielded by blackmatrix BM. Second portion CMT2 b is disposed between thin filmtransistor TFT2 and backlight BL, so that second portion CMT2 b canshield the light incident on the channel region from backlight BL.Because second portion CMT2 b has the function of shielding the light ofthe black matrix BM, a width of black matrix BM2 can be decreased, andan influence due to misalignment between thin film transistor substrateTFTB2 and counter substrate CF2 can be decreased. Second portion CMT2 bis integral with common wiring CMT2, and formed through the same processas common wiring CMT2, so that the manufacturing process does not becomecomplicated.

Second portion CMT1 b of display panel LCP1 has an effect similar tothat of second portion CMT2 b of display panel LCP1. In display panelLCP1, second portion CMT1 b is disposed on the observer side withrespect to thin film transistor TFT2, so that second portion CMT1 b canshield the light incident on the channel region from the natural light.

Thus, second portion CMT1 b and second portion CMT2 b act as a lightshielding unit that shields the light incident on the channel region ofthe thin film transistor. Consequently, a characteristic change of thethin film transistor due to the light incidence is prevented, so thatthe degradation of the display quality can be prevented.

Liquid crystal display device LCD of the first exemplary embodiment isnot limited to the above configuration. For example, as illustrated inFIGS. 3, 13, and 14, liquid crystal display device LCD of the firstexemplary embodiment may be configured such that a number of pixels PIX2(a number of pixel electrodes PIT2) per unit area of display panel LCP2is smaller than a number of pixels PIX1 (a number of pixel electrodesPIT1) per unit area of display panel LCP1. Specifically, in theconfiguration of FIGS. 14A and 14B, pixels PIX1 of display panel LCP1and pixels PIX2 of display panel LCP2 are disposed such that a ratio ofthe number of pixels PIX1 to the number of pixels PIX2 is 3:1. Threepixels PIX1 (red pixel PIXR, green pixel PIXG, and blue pixel PIXB) ofdisplay panel LCP1 and one pixel PIX2 of display panel LCP2 are disposedso as to overlap each other in planar view.

In liquid crystal display device LCD, display panel LCP1 may be disposedon the side of backlight BL, and display panel LCP2 may be disposed onthe observer side.

In the display panel (display panel LCP1 in FIG. 12 and the like)disposed on the observer side, second portion CMT1 b may be eliminatedin common wiring CMT1. Thus, in liquid crystal display device LCD of thefirst exemplary embodiment, it is only necessary to provide secondportion CMT2 b in at least the display panel (display panel LCP2 in FIG.12 and the like) disposed on the side of backlight BL. Therefore, atleast the light from backlight BL having the largest light amount can beshielded.

Second Exemplary Embodiment

Liquid crystal display device LCD according to a second exemplaryembodiment is constructed with display panel LCP1 (see FIG. 3) of thefirst exemplary embodiment while display panel LCP2 of liquid crystaldisplay device LCD of the first exemplary embodiment is eliminated. FIG.15 is a sectional view illustrating display panel LCP of the secondexemplary embodiment. FIG. 15 illustrates the sectional portion takenalong line B-B′ in FIGS. 7 and 8. In display panel LCP of the secondexemplary embodiment, thin film transistor substrate TFTB is disposed onthe side of backlight BL, and counter substrate CF is disposed on theobserver side. Second portion CMTb of common wiring CMT overlaps atleast a part of the channel region of thin film transistor TFT in planarview. Second portion CMTb may overlap the whole channel region of thinfilm transistor TFT or the whole region where thin film transistor TFTis formed in planar view. Consequently, the light incident on thechannel region of thin film transistor TFT from the natural light can beshielded.

Liquid crystal display device LCD of the second exemplary embodiment isnot limited to the above configuration. For example, as illustrated inFIG. 16, thin film transistor substrate TFTB may be disposed on theobserver side, and counter substrate CF may be disposed on the side ofbacklight BL. In the configuration of FIG. 16, second portion CMTb isdisposed between thin film transistor TFT and backlight BL and close tothe channel region, so that the light incident on the channel regionfrom backlight BL can be shielded.

The configuration of the pixel in liquid crystal display device LCD ofthe present disclosure is not limited to the configurations of the firstand second exemplary embodiments. For example, in the first and secondexemplary embodiments, the thin film transistor may be made of amorphoussilicon (a-Si) or oxide semiconductor.

In the first and second exemplary embodiments, the light shielding unit(second portions CMT1 b, CMT2 b, CMTb) overlapping the channel region ofthin film transistor TFT may be disposed in the floating state whileelectrically separated from the common electrode (CIT1, CIT2, CIT).

FIG. 17 is a plan view illustrating another pixel configuration ofdisplay panel LCP2 of the first exemplary embodiment. As illustrated inFIG. 17, second portion CMT2 b (light shielding unit) is disposed so asto overlap the channel region of thin film transistor TFT2 in planarview. Second portion CMT2 b may be integral with first portion CMT2 a ofcommon wiring CMT2, or formed in the floating state. Second portion CMT2(a hatched portion in FIG. 17) is larger than black matrix BM2 (a bolddotted-line portion in FIG. 17) in an area. Contact hole CH2 may be madeoutside the region of second portion CMT2 in planar view. Theconfiguration of the pixel in FIG. 17 can also be applied to displaypanel LCP1 of the first exemplary embodiment and display panel LCP ofthe second exemplary embodiment.

Although exemplary embodiments of the present disclosure are describedabove, the present disclosure is not limited to these exemplaryembodiments. It is noted that exemplary embodiments properly changedfrom the exemplary embodiments described above by those skilled in theart without departing from the scope of the present disclosure areincluded in the present disclosure.

1. A liquid crystal display device comprising: a first substrate formedwith a first gate line, a first source line, a first thin filmtransistor, and a first light shielding unit; a second substratedisposed opposite to the first substrate; and a first liquid crystallayer disposed between the first substrate and the second substrate,wherein the first light shielding unit is disposed between the firstthin film transistor and the first liquid crystal layer, and overlaps atleast a part of a first channel region of the first thin film transistorin planar view.
 2. The liquid crystal display device according to claim1, wherein a common electrode is further formed on the first substrate,and the first light shielding unit is made of a metallic material, andelectrically connected to the common electrode.
 3. The liquid crystaldisplay device according to claim 2, wherein a common wiring throughwhich a common voltage is supplied to the common electrode is furtherformed on the first substrate, and the first light shielding unit isintegral with the common wiring.
 4. The liquid crystal display deviceaccording to claim 1, wherein an organic insulator film is furtherformed on the first substrate, and the organic insulator film isdisposed between the first thin film transistor and the first lightshielding unit.
 5. The liquid crystal display device according to claim1, further comprising a backlight, wherein the first liquid crystallayer is disposed between the backlight and the first substrate.
 6. Theliquid crystal display device according to claim 1, wherein the secondsubstrate includes a black matrix, the black matrix overlaps at least apart of the first channel region in planar view, and the first lightshielding unit includes an overlapping region where the first lightshielding unit overlaps the black matrix and a non-overlapping regionwhere the first light shielding unit does not overlap the black matrix.7. The liquid crystal display device according to claim 1, furthercomprising: a third substrate formed with a second gate line, a secondsource line, and a second thin film transistor; a fourth substratedisposed opposite to the third substrate; and a second liquid crystallayer disposed between the third substrate and the fourth substrate,wherein the second substrate is disposed between the first liquidcrystal layer and the second liquid crystal layer.
 8. The liquid crystaldisplay device according to claim 7, further comprising a backlight,wherein the first liquid crystal layer is disposed between the backlightand the second substrate.
 9. The liquid crystal display device accordingto claim 1, further comprising: a third substrate formed with a secondgate line, a second source line, and a second thin film transistor; afourth substrate disposed opposite to the third substrate; and a secondliquid crystal layer disposed between the third substrate and the fourthsubstrate, wherein the first substrate is disposed between the firstliquid crystal layer and the second liquid crystal layer.
 10. The liquidcrystal display device according to claim 9, further comprising abacklight, wherein the first liquid crystal layer is disposed betweenthe backlight and the first substrate.
 11. The liquid crystal displaydevice according to claim 7, wherein a second light shielding unit isfurther formed on the third substrate, and the second light shieldingunit is disposed between the second thin film transistor and the secondliquid crystal layer, and overlaps at least a part of a second channelregion of the second thin film transistor in planar view.